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Lithium Intercalation in Anatase Titanium Vacancies and the Role of Local Anionic

EnvironmentJiwei Ma, Wei Li, Benjamin J. Morgan, Jolanta Światowska, Rita Baddour-Hadjean,

Monique Body, Christophe Legein, Olaf J. Borkiewicz, Sandrine Leclerc, Henri Groult, Frédéric Lantelme, Christel Laberty-Robert, and Damien Dambournet

Supporting InformationTable of content

Figure S1. X-ray diffraction diagrams of Ti1-x-yx+yO2-4(x+y)F4x(OH)4y samples prepared at 90, 110 and 130 °C......……….………………….……………….……………….……….………………………....3Figure S2. Experimental and fitted 19F solid-state MAS NMR spectra of Ti0.690.31O0.76F0.48(OH)0.76......……….………………….……………….……….……………….…....4Table S1. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.690.31O0.76F0.48(OH)0.76 and assignment of these NMR resonances......……….………………….……………….……………….…….………….…………….4Figure S3. Experimental and fitted 19F solid-state MAS NMR spectra of Ti0.790.21O1.16F0.44(OH)0.40......……….………………….……………….……………….…….………5Table S2. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.790.21O1.16F0.44(OH)0.40 and assignment of these NMR resonances......……….………………….……………….……………….…….………….…………….5Figure S4. Experimental and fitted 19F solid-state MAS NMR spectra of Ti0.870.13O1.48F0.36(OH)0.16......……….………………….……………….……………….…….………6Table S3. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.870.13O1.48F0.36(OH)0.16 and assignment of these NMR resonances......……….………………….……………….……………….…….………….………….....6Figure S5. Normalized 7Li MAS (20 kHz) NMR spectra of the chemically lithiated ((a) 0.2, (b) 0.5 and (c) 0.8 Li+ per formula unit) Ti0.78•0.22O1.12F0.40(OH)0.48 samples. Expansions of the central lines are shown in the insets: left, non-normalized spectra; right: normalized spectra...............................................………….………………………………………………………...7Table S4. Fluorine species occurring in Ti0.780.22O1.12F0.40(OH)0.48, 19F δiso values and relative intensities of the NMR lines of these species, conversion of these species in chemically lithiated samples, expected evolution of their 19F δiso values and potential occurrence of the fluorine species in the chemically lithiated samples…………………………………………......……….………….……..…………………………8Figure S6. Experimental and fitted 19F solid-state MAS NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.2 Li+ per formula unit)………….………………………………………………………….……………………………….9

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Table S5. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.2 Li+ per formula unit) and partial assignment of these NMR resonances......……….……..…………………………………………………………………………....9Figure S7. Experimental and fitted 19F solid-state MAS NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.5 Li+ per formula unit)…………………………………………………….……………….……………………………...10Table S6. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.5 Li+ per formula unit) and partial assignment of these NMR resonances......……………………….....................................................................................................10Figure S8. Experimental and fitted 7Li solid-state MAS NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit)…………………………………………………….……………….…...........................................11Table S7. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 19F MAS NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit) and partial assignment of these NMR resonances......……………..……..…………………………………………………………………….11Figure S9. Experimental and fitted 7Li solid-state MAS NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit)…………………………………………………….……………….…...........................................12Table S8. Isotropic chemical shifts, line widths and relative intensities of the NMR resonances used for the fit of the 7Li MAS NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit)…………………………………………………….……………………………………..12Figure S10. High energy x-ray diffraction patterns of Ti0.780.22O1.12F0.40(OH)0.48 pristine and chemically lithiated (0.2, 0.5 and 0.8 Li+ per formula unit)…………………………………………………….……………….……………………………...13Table S9. Values of the parameters used to describe the evolution of the activity coefficient (Eq. 6).…………………………………………………….……………….………………………………..13

Figure S11. DFT calculated relative energies for varying numbers of FO defects located at equatorial sites adjacent to the VTi vacancy, versus being separated. Source: The data set and code to generate this figure, and the figure file, are available under the MIT licence as part of Ref. 6 …………………......14

Figure S12. DFT calculated relative energies for varying numbers of OHO defects located at equatorial sites adjacent to the VTi vacancy, versus being separated. Source: The data set and code to generate this figure, and the figure file, are available under the MIT licence as part of Ref. 6. ………………………………………………………………………………………………………14

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Figure S1. X-ray diffraction diagrams of Ti1-x-yx+yO2-4(x+y)F4x(OH)4y samples prepared at 90, 110 and 130 °C.

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Figure S2. Experimental (in blue) and fitted (in red) 19F solid-state MAS (64 kHz) NMR spectra of Ti0.690.31O0.76F0.48(OH)0.76. The individual resonances used for the

fit are shown below (see Table S1).

Table S1. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (64 kHz)

NMR spectrum of Ti0.690.31O0.76F0.48(OH)0.76 and assignment of these NMR resonances.

iso LW I Assignment

-87.3 12.5 2.6 Ti3-F-3.9 35.3 60.5 Ti2o-F75.5 88.2 37.0 Tio2-F

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Figure S3. Experimental (in blue) and fitted (in red) 19F solid-state MAS (64 kHz) NMR spectra of Ti0.790.21O1.16F0.44(OH)0.40. The individual resonances used for the

fit are shown below (see Table S2).

Table S2. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (64 kHz)

NMR spectrum of Ti0.790.21O1.16F0.44(OH)0.40 and assignment of these NMR resonances.

iso LW I Assignment

-85.0 12.0 4.3 Ti3-F-1.6 35.5 66.0 Ti2o-F81.1 83.1 29.7 Tio2-F

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Figure S4. Experimental (in blue) and fitted (in red) 19F solid-state MAS (64 kHz) NMR spectra of Ti0.870.13O1.48F0.36(OH)0.16. The individual resonances used for the

fit are shown below (see Table S3).

Table S3. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (64 kHz)

NMR spectrum of Ti0.870.13O1.48F0.36(OH)0.16 and assignment of these NMR resonances.

iso LW I Assignment

-85.3 10.1 4.6 Ti3-F-1.2 35.3 64.8 Ti2o-F84.3 91.5 30.6 Tio2-F

7Li solid state MAS NMR spectra of the chemically lithiated samples were also recorded (Figure S5). The integrated intensity of the signal increases when the concentration of n-butyl lithium increases confirming the increasing insertion of lithium. Whereas paramagnetic compounds exhibit lithium resonances shifted over a range of several hundred ppm,1 due to the Fermi contact interaction, despite containing 3d1 titanium(III), lithiated Ti0.780.22O1.12F0.40(OH)0.48 samples, as lithiated anatase,2-4 show 7Li NMR resonances inside the normal diamagnetic 7Li shift range (ca. 5 to −5 ppm).5 Wagemaker et al.3 concluded that conduction,

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rather than paramagnetism, is the dominant interaction. Delocalized electron density is then also expected in the Ti0.780.22O1.12F0.40(OH)0.48 lithiated samples. As the Li rate increases, the 7Li signal becomes broadened and shifts slightly in a positive direction. Moreover, the intensity of the spinning sidebands increases from the lower to the intermediate rate. Assuming that MAS averages the dipolar interactions, the possible origins for the broad lines and the intense spinning sidebands are distributions of quadrupole interactions and chemical shifts due to disordered environments and interactions with electrons in the conduction band. Spectral decompositions of the slightly asymmetric central lines require two contributions (as an example, the fit of one the spectrum is given as SI (Figure S9 and Table S8)) which we have not been able to assign to the two Li host sites, i.e., titanium vacancies and interstitial site.

Figure S5. Normalized 7Li MAS (20 kHz) NMR spectra of the chemically lithiated ((a) 0.2, (b) 0.5 and (c) 0.8 Li+ per formula unit) Ti0.780.22O1.12F0.40(OH)0.48 samples.

Expansions of the central lines are shown in the insets: left, non-normalized spectra; right: normalized spectra.

Table S4. Fluorine species occurring in Ti0.780.22O1.12F0.40(OH)0.48, 19F δiso values (ppm) and relative intensities (I, %) of the NMR lines of these species, conversion of these species in chemically lithiated samples and expected evolution of their

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19F δiso values and potential occurrence of the fluorine species in the chemically lithiated samples.

F species in Ti0.690.31O0.76F0.48(OH)0.76

19F δiso I ConversionExpected

evolution of 19F δiso

Potential occurrence(1)

TiIVo2-F 98.0 31.9

TiIVo2-F =TiIIIo2-F ↘ xTiIVLio-F ↘ xTiIVLi2-F ↘↘ xTiIIILio-F ↘↘ xTiIIILi2-F ↘↘↘ xTiIVLi3-F ↘↘↘ xTiIIILi3-F ↘↘↘↘ x

TiIV2o-F -4.5 63.7

TiIV2o-F = x

TiIVTiIIIo-F ↘ xTiIII

2o-F ↘↘ xTiIV

2Li-F ↘ xTiIVTiIIILi-F ↘↘ x

TiIII2Li-F ↘↘↘ x

TiIV2Li2-F ↘↘ x

TiIVTiIIILi2-F ↘↘↘ xTiIII

2Li2-F ↘↘↘↘ x

TiIV3-F -88.5 4.4

TiIV3-F = x (low)

TiIV2TiIII-F ↘ x (low)

TiIVTiIII2-F ↘↘ x (low)

TiIII3-F ↘↘↘ x (low)

TiIV3Li-F ↘

TiIV2TiIIILi-F ↘↘

TiIVTiIII2Li-F ↘↘↘

TiIII3Li-F ↘↘↘↘

(1) The species TiIVo2-F are not observed in the chemically lithiated samples. Moreover, considering the preference of F for coordination numbers 1 and 2 with Ti, it can be assumed that fourfold coordinated F species including 3 Ti atoms do not occur in the chemically lithiated samples.

The intercalation of one Li+ ion being simultaneous with the reduction of Ti4+ into Ti3+ ion, if we consider the lithium intercalation into vacancy sites, Ti IVo2-F can be converted into TiIIIo2-F, TiIVLio-F, TiIVLi2-F, TiIIILio-F and TiIIILi2-F; TiIV2o-F can be converted into TiIVTiIIIo-F, TiIII2o-F, TiIV2Li-F, TiIVTiIIILi-F and TiIII2Li-F and TiIV3-F can be converted into TiIV2TiIII-F, TiIVTiIII2-F and TiIII3-F. Moreover, intercalation in interstitial sites leads to supplementary potential F species: TiIVLi3-F and TiIIILi3-F from TiIVo2-F, TiIV2Li2-F, TiIVTiIIILi2-F and TiIII2Li2-F from TiIV2o-F and TiIV3Li-F, TiIV2TiIIILi-F, TiIVTiIII2Li-F and TiIII3Li-F from TiIV3-F. Considering the preferential localization of F atoms close to vacancies, i.e., the preference of F for coordination numbers 1 and 2 with Ti, the fourfold coordinated F species including 3 Ti atoms are unlikely.

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Figure S6. Experimental (in blue) and fitted (in red) 19F solid-state MAS (34 kHz) NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.2 Li+ per formula unit). The individual resonances used for the fit are shown below (see Table S5).

Table S5. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (34 kHz)

NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.2 Li+ per formula unit) and partial assignment of these NMR resonances.

iso LW I Partial assignment

-204.3 8.8 25.6 Li6-F (LiF)-122.4 0.74 5.0 Adsorbed F-

-89.5 15.0 9.6 TiIV3-F, …

-53.0 48.0 28.1-7.1 38.2 31.8 TiIV

2o-F, …

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Figure S7. Experimental (in blue) and fitted (in red) 19F solid-state MAS (34 kHz) NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.5 Li+ per formula unit). The individual resonances used for the fit are shown below (see Table S6).

Table S6. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (34 kHz)

NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.5 Li+ per formula unit) and partial assignment of these NMR resonances.

iso LW I Assignment

-203.7 8.3 13.6 Li6-F (LiF)-200.7 17.7 21.4-122.3 0.70 12.8 Adsorbed F-

-90.7 13.2 3.8 TiIV3-F, …

-66.3 89.0 47.6-9.4 8.3 0.8 TiIV

2o-F, …

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Figure S8. Experimental (in blue) and fitted (in red) 19F solid-state MAS (34 kHz) NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit). The individual resonances used for the fit are shown below (see Table S7).

Table S7. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 19F MAS (34 kHz)

NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit) and partial assignment of these NMR resonances.

iso LW I Assignment

-203.8 7.8 9.8 Li6-F (LiF)-198.4 17.6 31.0-126.1 72.6 14.8-122.3 0.70 12.5 Adsorbed F-

-94.8 23.2 6.2 TiIV3-F,…

-61.2 58.5 25.8

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Figure S9. Experimental (in blue) and fitted (in red) 7Li solid-state MAS (20 kHz) NMR spectra of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit). The individual resonances used for the fit are shown below (see Table S8).

Expansions of the central lines are shown in the inset.

Table S8. Isotropic chemical shifts (δiso, ppm), line widths (LW, ppm) and relative intensities (I, %) of the NMR resonances used for the fit of the 7Li MAS (20 kHz)

NMR spectrum of Ti0.780.22O1.12F0.40(OH)0.48 chemically lithiated (0.8 Li+ per formula unit).

iso LW I

-0.13 5.1 46.4-0.29 12.1 53.6

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Figure S10. High energy x-ray diffraction patterns of Ti0.780.22O1.12F0.40(OH)0.48

pristine and chemically lithiated (0.2, 0.5 and 0.8 Li+ per formula unit).

Table S9. Values of the parameters used to describe the evolution of the activity coefficient (Eq. 6). F,TiO2 represents Ti0.780.22O1.12F0.40(OH)0.48.

Logarithms of the activity coefficients

ln f1 ln f2 ln f3 ln f4TiO2-Li -35 -58 -63 -950

F,TiO2-Li -40 -58 -63 -940

Concentrations at the transition points, cTj mol cm-3

cT1 cT2 cT3 cT4TiO2- Li 0.033 0.027 0.018 0

F,TiO2-Li 0.034 0.023 0.015 0

Steepness factors to describe the changes of the activity coefficient, Ψ1 cm3 mol-1

Ψ1 Ψ2 Ψ3 Ψ4TiO2-Li 320 320 650 650

F,TiO2-Li 220 250 230 260

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Figure S11. DFT calculated relative energies for varying numbers of FO defects located at equatorial sites adjacent to the VTi vacancy, versus being separated. Source: The data set and code to generate this figure, and the figure file, are

available under the MIT licence as part of Ref. 6.6

Figure S12. DFT calculated relative energies for varying numbers of OHO defects located at equatorial sites adjacent to the VTi vacancy, versus being separated. Source: The data set and code to generate this figure, and the figure file, are

available under the MIT licence as part of Ref. 6.6

References：1. Messinger, R. J.; Ménétrier, M.; Salager, E.; Boulineau, A.; Duttine, M.; Carlier, D.; Ateba Mba, J.-M.; Croguennec, L.; Masquelier, C.; Massiot, D.; Deschamps, M., Revealing Defects in Crystalline Lithium-Ion Battery Electrodes by Solid-State NMR: Applications to LiVPO4F. Chem. Mater. 2015, 27 (15), 5212-5221.

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2. Luca, V.; Hanley, T. L.; Roberts, N. K.; Howe, R. F., NMR and X-ray Absorption Study of Lithium Intercalation in Micro- and Nanocrystalline Anatase. Chem. Mater. 1999, 11 (8), 2089-2102.3. Wagemaker, M.; van de Krol, R.; Kentgens, A. P. M.; van Well, A. A.; Mulder, F. M., Two Phase Morphology Limits Lithium Diffusion in TiO2 (Anatase):  A 7Li MAS NMR Study. J. Amer. Chem. Soc. 2001, 123 (46), 11454-11461.4. Lo, A. Y. H.; Schurko, R. W.; Vettraino, M.; Skadtchenko, B. O.; Trudeau, M.; Antonelli, D. M., Solid-State 23Na and 7Li NMR Investigations of Sodium- and Lithium-Reduced Mesoporous Titanium Oxides. Inorg. Chem. 2006, 45 (4), 1828-1838.5. Günther, H., Lithium NMR in Encyclopedia of Nuclear Magnetic Resonance. John Wiley & Sons, Ltd: Chichester: 2007; p 1-21.6. Morgan, B. J., DFT Data Analysis: Intercalation of X=(Li, Na, Mg, Ca, Al) into (F/OH)-substituted anatase TiO2. Zenodo 2017, http://doi.org/10.5281/zenodo.1181872.

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